you can use the key-combination Alt-Down or Alt-Up from the search field to expand the complete search history (and use the up/down arrow keys to navigat to the search query you want.

Or type Ctrl-Space in the search field. Even better: if you want to search for "random" and you searched for that before, type for example "ra", followed by Ctrl-Space and all search queries that contain " ra" will be shown in the drop-down list. This means you can also search for "nd" to find "random".

Ctrl-Shift-H is another option to open entries from your search history. You can also use this to manage your entries (add, remove, ...)